"Can you add polyurethane to the nape of a wig cap to make it more secure? I don't like the wig grip or glue."
Yes! You can add a poly tab to your wig if you are comfortable doing DIY customizations. We offer the polyurethane in sheets HERE:
And we also have entire pre-cut kits HERE to make this an easy at-home project. Heather uses the Milano kit in one of her Clary's and he says it's a life saver on windy days!